1. Field of the Invention
The invention relates to a stereoscopic video display method and apparatus, a stereoscopic video system, and a stereoscopic video forming method, a natural stereoscopic sense can be obtained by limiting a parallax amount between a target and another object.
2. Description of the Related Art
When the person sees a target, a focal point is set only to a position near the target existing at a center of a field of view and an object existing at a position of out-of-focus is recognized as a blurred object. Therefore, the person hardly recognizes a large parallax.
For example, a method and an apparatus which can obtain effectively a stereoscopic sense of not only a moving object but also a still object from a 2-dimensional video signal (composite color video signal) are disclosed in JP-A-10-276455.
FIG. 1 shows a block diagram of such an apparatus and relates to an example of a projection type display using two projectors for displaying right and left video images, respectively. The position in the horizontal direction on a screen is controlled in accordance with boundary information of an inputted video signal, thereby generating a parallax between the right and left video images.
A 2-dimensional video signal supplied to an input terminal 51 is supplied to a Y/C separating circuit 52, by which a luminance signal Y and a chrominance signal C are separated. The chrominance signal C is supplied to a color demodulating circuit 53. The color demodulating circuit 53 performs a color demodulation to the supplied chrominance signal C, thereby generating two color difference signals (R-Y and B-Y). The luminance signal Y is supplied to a variable delay circuit 54L. The color difference signals R-Y and B-Y are supplied to delay circuits 55L and 56L each having a fixed delay amount. A symbol xe2x80x9cLxe2x80x9d indicates a left video signal path. A right video signal path is expressed by a symbol xe2x80x9cRxe2x80x9d. Since the right video signal path is similar to the left video signal path, its description is omitted.
Output signals of the variable delay circuit 54L and delay circuits 55L and 56L are supplied to a matrix circuit 57L. Three primary color signals R, G, and B are formed by the matrix circuit 57L and supplied to a CRT driving circuit 59L through a preamplifier 2558L.
A CRT 60L for projection is driven by the CRT driving circuit 59L and a left video image is displayed on a screen 62. Similarly, a CRT 60R for projection is driven by a CRT driving circuit 59R and a right video image is displayed on the screen 62. In this instance, the right and left video images are overlapped and displayed so as not to be deviated to the same position on the screen 62. The left video image which is projected by the CRT 60L is an image which passed through a horizontal polarizing filter 61L. On the other hand, the right video image which is projected by the CRT 60R is an image which passed through a vertical polarizing filter 61R.
By using glasses 63 having a horizonal polarizing filter 64L for the left eye and a vertical polarizing filter 64R for the right eye, the user can separately see the video images displayed on the screen 62 by the CRTs 60L and 60R.
The left and right video images having parallax information are formed being controlled so as to deviate the horizontal positions of the left and right video images in the opposite directions in accordance with boundary information in the inputted video signal by the variable delay circuits 54L and 54R. In case of an object having a large amount of boundary information, the object image is determined to be a foreground. On the other hand, in case of an object having a small amount of boundary information, the object image is determined to be a background. The amount of boundary information is detected on the basis of the luminance signal Y from the Y/C separating circuit 52. That is, a detection signal Sd is formed by allowing the luminance signal Y to pass through a high pass filter 65 and a rectifying circuit 66.
The high pass filter 65 detects a high frequency component in the luminance signal Y. The high frequency component includes pulses of a positive polarity and a negative polarity. The rectifying circuit 66 rectifies an output signal of the high pass filter 65 and generates the detection signal Sd having a positive or negative polarity.
The detection signal Sd is supplied to the variable delay circuit 54L as a signal to control the delay amount and also supplied to an inverter 67. A detection signal Sdxe2x80x2 inverted by the inverter 67 is supplied to the variable delay circuit 54R as a signal to control the delay amount.
By supplying the detection signals Sd and Sdxe2x80x2 to the variable delay circuits 54L and 54R, the positions in the horizontal direction of the left and right video images are controlled so as to mutually move in the opposite directions, thereby allowing an image of the object having the boundary information to be formed as a fusion image onto one of the front and rear surfaces of the screen 62.
It is, therefore, an object of the invention to provide stereoscopic video display method and apparatus which can obtain a natural stereoscopic sense of limiting a parallax as compared with the existing stereoscopic video display method.
It is an object of the invention to obtain a stereoscopic sense of a parallax between the right and left eyes and provide a stereoscopic video system which gives a relative parallax limited to a value within a predetermined amount between a foreground and a background which are discriminated from a video signal.
A clue of a foreground/background relation is extracted from a video signal inputted to a foreground/background discriminating circuit based on a focus, color difference signals, and a luminance signal. An amplitude is limited for the extracted clue, and a control signal is supplied to variable delay circuits for delaying a right video image and a left video image. In the variable delay circuits, a delay according to a level of the control signal is performed synchronously with the control signal and the right and left video images are outputted.
It is an object of the invention to provide a stereoscopic video system comprising means for giving a relative parallax to a foreground and a background which are discriminated from right and left video signals photographed by two cameras and means for limiting the relative parallax to a value within a predetermined amount and to provide a stereoscopic video forming method for such a system.
Since a parallax between a target and another object is expressed only by the relative parallax instead of an absolute parallax, a natural stereoscopic image can be realized. Since field memories are not used when converting 2-dimensional video images to a 3-dimensional video image, the circuit scale can be small enough.